The invention relates to a process for treating, preferably for reducing, material in particle form in at least one fluidization zone at elevated temperature, in particular for reducing fine ore, the particulate material being held in the fluidization zone by a treatment gas which flows upward from below. Material in fine particle form which is discharged from the fluidization zone with the treatment gas is separated out of the treatment gas in a deposition zone. The following steps are carried out in the deposition zone: feeding the stream of treatment gas and discharged material in fine particle form to a separating device, separating the finely particulate material from the treatment gas, the treatment gas being extracted from the separating device as off-gas, and removing the separated finely particulate material from the separating device, and to an apparatus for carrying out the process.
In fluidized-bed systems, the separation of material in fine particle form, i.e. fine dust, which is discharged or entrained from the fluidization zone with the treatment gas, is of considerable importance.
It is desirable for the fine dust to be separated from the treatment gas as completely as possible, in order on the one hand to avoid loss of material and in order on the other hand to avoid caking originating from the fine dust carried in the treatment gas in a further process, in which the off-gas extracted from the separating device is generally once again used as a treatment gas.
Fine dust has poor flow properties in particular in the hot state and tends to cause blockages and caking in cyclone outlets and inlets. In extreme cases, fine-dust return lines may even become blocked up.